The alpha-herpesvirus herpes simplex virus type 2 (HSV-2) is the cause of genital herpes, which can be treated symptomatically but not cured. Hallmarks of herpes virus infection include the establishment of lifelong, latent infections that can reactivate to cause one or more rounds of disease, as well as transmission in the absence of symptoms. Transmission of HSV-2 to newborns at the time of delivery may lead to devastating systemic infection with encephalitis. Further, immunocompromised individuals are at increased risk of serious disseminated infection. Also, HSV-2 has been shown to increase significantly the risk of becoming infected with HIV-1, the virus that causes AIDS. The development of vaccines to prevent or treat HSV-2 infection is therefore of considerable importance.
The manufacture of virus-based vaccines (e.g., attenuated or inactivated virus particles) generally involves the infection of mammalian cell lines in vitro with a small quantity of a virus, followed later by harvest of large quantities of progeny virus. The mammalian cells are propagated in growth media, which are complex solutions containing a large number of different salts, small organic molecules such as carbohydrates and lipids, and macromolecules such as peptides and proteins. Optimization of virus production methods is important to the development of efficiently produced, cost-effective herpes virus vaccines.